I have just bought myself a new laptop. I got a Lenovo G570 from PC World for just under £450. It seems pretty good Intel i5 processor with 4GB Ram.
Installed the 64 bit version of Ubuntu 11.10. Installation went without hitch. Initial boot hang for some reason, but switching it off and on again solved that, and it has worked fine since. Basically everything I have tried worked out of the box - screen, track pad mouse, web cam, USB. Therefore absolutely no issues - a very good advert for Lenovo and Ubuntu.
I was really surprised at how powerful it is - I just installed a simple OSM tile server on it using the instructions at http://wiki.openstreetmap.org/wiki/Ubuntu_tile_server. Loading the british isles OSM data extract took less than 2 hours. My home server (ex laptop) - an intel dual core processor and 2GB Ram running 32 bit Ubuntu takes almost 24 hours.
I am thinking I should have bought 2 of them and use one as the server - it only uses 20 Watts when running at low load, which is probably less than my existing one.....